/**
 * Created with IntelliJ IDEA.
 * Description无头双向链表实现
 * User: YCKOKO
 * Date: 2022-11-03
 * Time: 22:28
 */
public class MyLinkedList {
    static class ListNode{
        public int val;      //节点值
        public ListNode prev;//节点前驱
        public ListNode next;//节点后驱

        public ListNode(int val){
            this.val = val;
        }
    }
    public ListNode head;//头结点
    public ListNode tail;//尾节点

    //得到单链表的长度
    public int size(){
        int count = 0;
        ListNode cur = this.head;
        while(cur != null){
            cur = cur.next;
            count++;
        }
       return count;                                                                                                                                                                                                                                                                                                                  return count;
    }
    public void display(){
        ListNode cur = this.head;
        while(cur != null){
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
    }

    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(this.head == null){
            this.head = node;
            this.tail = node;
        }else{
            node.next = this.head;
            this.head.prev = node;
            this.head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(this.head == null){
            this.head = node;
            this.tail = node;
        }else{
            this.tail.next = node;
            node.prev = this.tail;
            this.tail = node;
        }
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if(index<0 || index>this.size()){
            throw new IndexWrongFulException("输入的下标不合法");
        }
        ListNode node = new ListNode(data);
        if(index == 0){
            addFirst(data);
            return;
        }
        if(index == this.size()){
            addLast(data);
            return;
        }
        ListNode cur = FindIndexListNode(index);
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
        node.next = cur;
    }

    public ListNode FindIndexListNode(int index){
        ListNode cur = this.head;
        while(cur != null && index != 0){
            cur = cur.next;
            index--;
        }
        return cur;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                if(cur == this.head){
                    this.head = this.head.next;
                    if(this.head == null){
                        this.tail = null;
                    }else{
                        this.head.prev = null;
                    }
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next == null){
                        this.tail = cur.next;
                    }else{
                        cur.next.prev = cur.prev;
                    }

                }
                return;
            }else{
                cur = cur.next;
            }
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                if(cur == this.head){
                    this.head = this.head.next;
                    if(this.head == null){
                        this.tail = null;
                    }else{
                        this.head.prev = null;
                    }
                }else{
                    cur.prev.next = cur.next;
                    if(cur.next == null){
                        this.tail = cur.prev;
                    }else{
                        cur.next.prev = cur.prev;
                    }
                }
                cur = cur.next;
            }
            else{
                cur = cur.next;
            }

        }
    }
    public void clear(){
//        ListNode cur = head;
//        while(cur != null){
//            ListNode curNext = cur.next;
//            cur.next = null;
//            cur.prev = null;
//            cur = curNext;
//        }
        this.head = null;
        this.tail = null;
    }
}
